Risk Management and Use of Financial Instruments - Terms and Fair Values of Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Notional Amount	$ 328,610	$ 278,610
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 3.623% Interest Rate Swap Maturing February 1, 2019 [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Notional Amount	$ 0	200,000
Derivative, Fixed Interest Rate	3.623%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ 0	(2,649)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 3.300% Interest Rate Swap Maturing January 30, 2021 [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Notional Amount	$ 25,774	25,774
Derivative, Fixed Interest Rate	3.30%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ (531)	(334)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 3.090% Interest Rate Swap Maturing October 30, 2019 [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Notional Amount	$ 25,774	25,774
Derivative, Fixed Interest Rate	3.09%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ (388)	(254)
Other Liabilities [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 2.750% Interest Rate Swap Maturing September 30, 2017 [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Notional Amount	$ 27,062	27,062
Derivative, Fixed Interest Rate	2.75%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ (201)	(253)
Other Assets [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| 3.718% Interest Rate Swap Maturing October 8, 2022 [Member]
Derivatives Fair Value [Line Items]
Derivative, Fixed Interest Rate	3.718%
Derivative Asset, Notional Amount	$ 250,000	0
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	$ 1,884	$ 0

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5580258-113959

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+ References

No definition available.

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+ References

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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959

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No definition available.

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